Paper No. 11
Presentation Time: 4:15 PM
REMOTE SENSING CONTRIBUTIONS TO RAINFALL - RUNOFF MODELING OF THE PISHIN LORA BASIN, PAKISTAN
Construction and calibration of rainfall-runoff models for many of the World’s watersheds is hampered by their inaccessibility and absence of adequate field measurements. We adopted methodologies that heavily rely on readily available remote sensing datasets for the assessment, management, and hydrologic modeling of the water resources of such remote and inadequately gauged regions. The Soil and Water Assessment Tool was selected for continuous (1998-2005) rainfall-runoff modeling of the NE part of the Pishin Lora basin (NEPL), a politically unstable area that is lacking adequate rain gauge and stream flow data. To account for the paucity of rain gauge and stream flow gauge data, inputs to the model included satellite-based TRMM precipitation data and modeled runoff was calibrated against satellite-based observations. These include: (1) monthly estimates of the water volumes impounded by the Khushdil Khan and the Kara Lora reservoirs, and (2) inferred wet versus dry conditions in streams across the NEPL throughout the examined period. Calibrations were also conducted against observed flow reported from the Burj Aziz Khan station at the NEPL outlet. Model simulations indicate: (1) average annual precipitation (1998-2005), surface runoff, and net recharge are 1,300 x 106 m3, 148 x 106 m3, and 361 x 106 m3, respectively; (2) within the NEPL watershed, precipitation and runoff are high for the NE (precipitation: 194 mm/y; runoff: 38 x 106 m3/y) and NW (134 mm/y; 26 x 106 m3/y) basins compared to the southern basin (124 mm/y; 8 x 106 m3/y); and (3) construction of delay action dams in the NE and NW basins of the NEPL could increase recharge from 361 x 106 m3/y up to 432 x 106 m3/y and achieve sustainable extraction. The adopted methodologies should not be considered as a substitute for traditional field-based approach, provide first order estimates for rainfall, runoff, and recharge in the arid and semi-arid parts of the World that are inaccessible and/or lack adequate coverage with stream flow and precipitation data.